I use a half inch ratchet on bottom, and a 1/2" impact gun on the top. I haven't had the misfortune of cutting myself changing them(yet), ..but I never even come into contact with the blades this way. For the WB's, I do them the same way. I did pick up a blade blocker for $ 7 from Blue Blazes in Kentucky last fall . It's simple in design, but works great for changing 21's.